[Tutor] calling and returning functions.

Dave Angel davea at davea.name
Mon Feb 11 21:20:05 CET 2013

On 02/11/2013 03:07 PM, Pravya Reddy wrote:
> Can you please complete the code.
> #!/usr/bin/env python
> """ One function receives a value in inches and returns the equivalent
> value in
> cms like cm = 2.54 * in.The other function receives a value in cms and
> returns
> the equivalent value in inches like in = cm / 2.54."""
> def conversion(inch,cm):
>      """returns the value in cm and in."""
>      return (2.54 * float(inches))
>      return (float(cm) / 2.54)

This second line does nothing, since the first line always returns.
But it doesn't matter much, since you never call it.  Don't you want two 

> def GetInt(prompt):
>      """Returns a number, or None if user doesn't answer."""
>      while True:
>          said = input(input(prompt))

This has been corrected several times, by various people.  What do you 
think it does, and what do you wish it would do?  Is there ever a reason 
to call input with the results of a call to input?

>          if not said:
>              return None
>          try:
>              number = int(said)
>          except ValueError:
>                  print (said, "is not a number.")
>                  continue
>                  return number

The return never gets executed, since it follows an unconditional 
continue statement.  Do you perhaps want it dedented?

> def Test():
>      first = GetInt('Please enter inches:')
>      if first:
>          second = GetInt('Please enter cms:')

Do you always want to do a pair of conversions?  if not, why are you 
asking for both values before doing anything?

>          print(first, "*", 2.54, "=", "cms")

This prints an equation without actually printing a result.

>          print(second, "/", 2.54, "=", "in")


> Test()


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